A communication system provides for the communication of information between a sending station and a receiving station by way of a communication channel. Information to be communicated by the sending station to the receiving station is converted into a form to permit its communication upon the communication channel. A wide variety of different types of communication systems have been developed and are regularly utilized to effectuate communication of information between sending and receiving stations.
New types of communication systems have been, and continue to be, developed and constructed as a result of advancements in communication technologies. A radio communication system is representative of a type of communication system which has benefited from advancements in communication technologies. Increased communication mobility is provided in a radio communication system as radio links are utilized to form communication channels upon which the information is communicated. In contrast, in a wireline communication system, wireline connections are required to form a communication link between sending and receiving stations.
The communication capacity of a radio communication system, however, is sometimes constricted by bandwidth limitations. Only a limited amount of the electromagnetic spectrum is allocated to be used by a particular radio communication system. In other words, when the communication capacity is limited by the bandwidth allocated to the radio communication system, an increase in communication capacity requires more efficient utilization of the available bandwidth.
Digital communication techniques, for instance, can be used in a manner by which to increase the bandwidth efficiency of communications upon a communication channel in a communication system. Due to the particular need to efficiently utilize the bandwidth allocated in the radio communication system; the use of such digital techniques is particularly advantageously utilized in a radio communication system.
Digital communication techniques typically involve digitizing information, i.e., data, which is to be communicated into digital form to form digital bits. The digitized bits are sometimes formatted to form packets of digital bits. Packets of data are communicated in a packet data system at discrete intervals and, subsequent to reception at a receiving station, connected theretogether to recreate the informational content of the data.
Because packets of data can be communicated at discrete intervals, a frequency band need not be dedicated solely for the communication of data generated by one sending station for transmission to one receiving station, as conventionally required in analog communications. Instead, the frequency band can be shared amongst a plurality of different sending and receiving station pairs. Because the same frequency band can be utilized to effectuate communications by the plurality of pairs of communication stations, improved communication capacity is possible.
Conventional LANs communicate packets of data to effectuate communications therein. Wireless networks, operable in manners analogous to LANs, referred to as WLANs (Wireless Local Area Networks) have also been developed and are utilized to communicate data over a radio link.
The standards of operation of an exemplary WLAN are set forth in the IEEE (Institute of Electrical and Electronic Engineers) 802.11 specification. The standard set forth in the specification provides for multi-user communications. Data is formatted into packets and sent over a radio link.
As presently promulgated, the IEEE 802.11 specification defines a Contention Period (CP) and Contention Free Period (CFP). The contention period defines a random access period during which any sending station is permitted random access to communicate data. And, the contention free period defines a period in which data is permitted to be communicated responsive to a polling procedure n which allocations are made as to when a sending station is permitted to communicate a frame of data.
Point Coordinate Function (PCF) and Distributed Coordination Function (DCF) procedures are also defined. These functions are access methods defined in the IEEE 802.11 standard. DCF, a mandatory function defines the CP, and PCF, an optional function, defines the CFP.
Proposals have been set forth by which to adopt the IEEE 802.11 WLAN standard as a European WLAN standard. However, IEEE 802.11 standard, as presently promulgated, fails to include a Transmission Power Control (TPC) scheme. A transmission power control scheme is required to be implemented in a WLAN system in Europe.
If a manner could be provided by which to provide a transmission power control scheme to a WLAN system constructed otherwise according to the IEEE 802.11 standard, the resultant system could be adopted as a European WLAN standard.
It is in light of this background information related to radio communication systems that the significant improvements of the present invention have evolved.